If another pitcher tears his latissimus dorsi muscle from the bone in the back of his shoulder, has it surgically repaired and returns to a major-league mound, he should thank his surgeon for successfully performing Jake Peavy surgery.

The Giants' newest starter is still pitching in the majors at age 33 because he trusted a surgeon in Chicago to perform an experimental operation to reattach the "lat" after Peavy tore his completely while throwing a pitch during a July 2010 game at U.S. Cellular Field.

Peavy was pitching for the White Sox, whom he will face at AT&T Park on Wednesday.

"It was excruciating," Peavy said. "It was a tough blow. It was painful."

Not as painful as the realization that a big-league career that began with the Padres in 2002 and brought him the National League Cy Young Award five years later could be over at 29.

Peavy stared at that reality squarely, because the injury was rare and there was no history of a pitcher with a 100 percent lat tear returning to the mound with the same effectiveness.

He was fortunate to be pitching in the right city. A Chicago surgeon named Dr. Anthony Romeo saw Peavy and proposed an operation that had not been tried on a ballplayer. Romeo would reattach the lat using stitches and anchors.

"We certainly knew we were in uncharted waters," Peavy said last week after falling to 0-3 with the Giants with a loss in Milwaukee. "We sought all kinds of medical opinions and did our research to see the history of lat injuries. There was some history, but never to the point of 100 percent being detached and retracted down to my back to where they would have to go get it and stitch it up, put some anchors in and reattach it."

Romeo had a lot of experience treating players with lat tears. In a 2012 interview with MLB.com, he said Peavy had less than a 50 percent chance of returning to an "elite level of pitching" without the experimental surgery.

Peavy trusted Romeo. He had no choice.

"I certainly thought and knew it was a very real possibility that I could never regain the form again to be able to pitch at this level," Peavy said. "It was tough. But at the end of the day, you exhaust every option so if that were to be the case, and you couldn't come back, you did everything in your power to try to get it right."

Other pitchers have been diagnosed with partial tears, including Roy Halladay, Kerry Wood and Tom "Flash" Gordon. But that is not one of the first areas physicians examine when a pitcher refers to posterior shoulder pain.

Peavy said his injury resulted from a "perfect storm" of happenstance. He unknowingly had changed his delivery to compensate for an ankle injury from earlier in 2010. Had Peavy still been with the Padres, his pitching coach or manager might have noticed. But he was with the White Sox after a 2009 deadline trade and his new coaches were less attuned to how he was supposed to throw.

Peavy believes he placed extra strain on the lat, which was partially torn already, and on the fateful pitch to the Angels' Mike Napoli on July 6, it snapped.

Nobody had performed the surgery that Romeo proposed because nobody thought the repair could withstand the force of throwing 100 pitches a game. Peavy knew that going in.

"When I sat down with Dr. Romeo, he was very straightforward and to the point and very confident of what he thought he was going to be able to do, and he was right," Peavy said. "I owe so much to that man, and we're still to this day great friends."

Peavy returned to the mound in May 2011 - too soon, he now understands. But in 2012, he was an American League All-Star. A year later, he helped the Red Sox win a World Series.

The surgery left some permanent hardware in Peavy's shoulder. As he put it, "I'm put together differently than previous to the injury, so things are different the way my arm works. Mechanically, we had to do some things different than I've done in the past," namely throwing out of a different arm slot.

But he added, "It doesn't bother me. I've been very fortunate and blessed to be able to put it behind me."

Peavy smiled at the notion of a surgery named for him and said he hopes his experience helps pitchers stay off the operating table by encouraging team physicians to look more often at the lat as a source of shoulder pain.

A partial tear can heal as scar tissue builds, but the pitcher needs to step away from the game for an extended period.

Peavy also knows this surgery of last resort can save careers the way it saved his.

"I was pitching at a high level," he said, "and believe I can for years to come."